Reports from Karen State in eastern Burma say that the army's annual dry season offensive against the Karen National Union is under way. The KNU has been fighting for freedom from the military government for almost 60 years. In the past two years, rights groups say the Burmese army has intensified a scorched earth campaign in Karen State, resulting in a growing humanitarian crisis. Rory Byrne and Wido Schlichting report from the Thai-Burma border.

The war between the Burmese army and the Karen ethnic minority in Burma is thought to be the world's longest running civil war. War broke out in 1949, shortly after the 1948 independence from Britain, when the Karen were denied autonomy from the government in Rangoon, dominated by ethnic Burmese.

Burma's military government justifies its harsh rule in part by saying it is necessary to keep different ethnic groups from trying to split the country. Over the years, more than 17 ethnic groups have fought the government, although in the past decade several signed peace agreements. But in Karen State the fighting continues and villagers are caught in the middle.

Human rights groups say the Burmese army uses scorched-earth tactics to deny Karen guerrillas a support base. Villagers are killed or forced to flee, livestock are shot, homes are burned and landmines are laid to prevent people from returning.

Aid groups say that about 370 villagers have been killed since late 2006. About 30,000 have been displaced.

Debbie Stothard is the coordinator for the Alternative ASEAN Network on Burma. She told us, "In the past two and a half years we have seen no let up in the attack – it's no longer a seasonal offensive, it's an on-going intense offensive and that has meant that people – many, many communities – have not been able to grow rice for two years. Twenty five thousand people are facing imminent starvation."

Human rights groups say that the army often uses captured civilians as forced labor. The Karen say they want peace but, without a peace agreement, they will keep fighting.

Johnny is the commander of the KNU's seventh brigade based on the Thai-Burma border. "Even though we are less in number, what we need is sacrifice, perseverance and unity, so then one day we will certainly obtain our victory and surely achieve our goal," he says.

Sann Aung is a cabinet minister with Burma's government-in-exile, based in Bangkok. He tells VOA, "They would like to negotiate a ceasefire. They have had many talks with the military regime, but the military regime demands their total surrender. That is not acceptable to the KNU [Karen National Union]. That is the situation."

Aid groups expect that in the coming months, thousands more Karen will be forced to flee and more lives will be lost.